Field of the Invention
The present invention relates to an image pickup device, an image pickup system, a driving method for an image pickup device, and a driving method for an image pickup system.
Description of the Related Art
As an image pickup device including an AD converter for each column (an AD converter provided for each column is hereinafter referred to as a column ADC) in a CMOS image sensor (may also referred to as a CMOS sensor) used in a recent digital camera, an image pickup device disclosed in Japanese Patent Application Laid-Open No. 2012-004727 has been known.
In the image pickup device according to Japanese Patent Application Laid-Open No. 2012-004727, the column ADCs average the results of sampling the reset level signals of the pixels a plurality of times. Thus, the image pickup device according to Japanese Patent Application Laid-Open No. 2012-004727 outputs the signal in which the lower random noise caused in the pixels and the column ADCs is reduced.
However, in the image pickup device according to Japanese Patent Application Laid-Open No. 2012-004727, an analog signal is subjected to the AD conversion a plurality of times for reducing the random noise; therefore, the AD conversion time has been long.